1. Field of the Invention
The present invention relates to an automatic sewing machine, and more particularly to a sewing direction control apparatus for sewing machine.
2. Description of the Prior Art
Computer control sewing machines are usually used to embroider complicated patterns automatically rather than manually, whereby to enhance the quality of the embroidery pattern, or used to stitch buttons or create decorative patterns on sewing products, whereby to improve sewing speed or accuracy. The existing computer control sewing machine essentially comprises a clamp on a work platform to clamp and fix the sewing product to be embroidered, the clamp is driven by a movement device to perform two-dimensional movement on the work platform with respect to the sewing head of the sewing machine, and the sewing product will move along with the clamp, so that patterns can be embroidered on the sewing product.
The sewing head of the existing computer control sewing machines is designed to be able to sew the sewing product only in a specific direction, so that the sewing product has to be inserted from the specific direction into the sewing head and should be aligned to the needle, then the sewing thread above the sewing machine can be formed into a loop to form lock stitch seam by cooperating with the sewing thread from the thread spool which is at the lower portion of the sewing machine. However, when moving in a two-dimensional manner along the work platform, the sewing product might approach the needle from any direction, resulting in poor stitching or deviation of sewing thread.
To solve the above defects, U.S. Pat. No. 4,498,404 discloses an automatic sewing apparatus which uses a manipulator arm to replace the conventional 2D movement device. The manipulator arm includes three rotation axes, so that the sewing product can be better controlled by the manipulator arm to rotate between the needle and the work platform, ensuring that the sewing product is kept being inserted into the sewing head from a specific direction. An Italian patent B093A 000113 discloses another sewing apparatus, wherein a lever with a needle is arranged above the needle plate of the sewing head, and below the needle plate is disposed a thread shaft with a hook. The lever and the thread shaft rotate together to maintain the relative position between the needle and the hook unchanged, ensuring that the sewing product is kept being inserted into the sewing head from a specific direction.
However, the above two sewing apparatuses still have the following disadvantages:
1. for automatic sewing machines, the sewing product must be moved intermittently and rapidly a very small distance at a time during sewing operation, so that the manipulator arm for moving the sewing product should have excellent acceleration ability and should be capable of precisely controlling the distance that the sewing product moves, resulting in a high manufacturing and maintenance cost of the manipulator arm.
2. there are various types of automatic sewing machines, however, the positioning device which maintains the relative position between the needle and the hook unchanged by using the synchronous rotation of the lever and the thread shaft is inapplicable to the sewing machines with cylinder bed head. Therefore, it is still unable to solve the sewing direction problem.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.